var obj = {
  _age: 18,
  set age(value) {
    this._age = value
    console.log("执行");
  },
  get age() {
    return this._age
  }

}

Object.defineProperties(obj, {
  name: {
    configurable: true,
    enumerable:true,
    writable:true,
    value: 'halo'
  },
  age: {
    configurable: true,
    enumerable:true,
    get: function() {

    },
    set: function() {

    }
  }
})

console.log(obj.age);
console.log(obj);